Who is Ogier Ghislain de Busbecq, Carolus Clusius, and Sultan Ahmed from The Botany of Desire and what is their importance?

Ogier Ghislain de Busbecq (1520 - 1592), ambassador of the Austrian Hapsburgs to the court of Süleyman the Magnificent in Constantinople, is said to have originally introduced tulip bulbs from Turkey to Europe circa 1554. Because of this royal court-to-court transfer, the tulip was established as a royal flower. Much of the resultant European history of the tulip is recounted in the text, with a particular focus on the tulipomania in Holland, which reached a peak in 1636-1637.